The Obama Administration has significantly expanded the number of stem-cell lines that may now be eligible for study using federal funds. Since 2001, under a Bush Administration ban, no new stem-cell lines could be created or studied using government dollars (though financing was allowed for research on a few dozen or so stem-cell lines that were already in existence), but some estimates suggest that since Bush's policy was implemented, as many as 700 new human embryonic-stem-cell lines have been created through private funding, mostly using embryos discarded by IVF clinics  and many of those lines may now qualify for public funding. (Read "Stem Cell Research: The Quest Resumes.")

"The guidelines allow NIH to fund scientifically worthy research using responsibly derived human embryonic stem cells," Dr. Raynard Kington, acting director of the agency, said in a telebriefing with reporters on Monday.

The new rules, which also establish the first federal registry of eligible stem-cell lines, were immediately applauded by scientists and by various patient advocacy groups. "These guidelines will bring us closer than ever toward unleashing the promise of embryonic-stem-cell-research and maximizing its therapeutic potential for patients with Type 1 diabetes," said Alan Lewis, president of the Juvenile Diabetes Research Foundation.

Starting Tuesday, all U.S. stem-cell researchers must follow the NIH guidelines in creating new stem-cell lines in order to receive federal support. For all lines created before Tuesday, researchers may now receive federal funds if the creation of their stem-cell lines adhered to the spirit, if not the letter, of the new regulations.

The guidelines allow the NIH to fund the creation and study of new stem-cell lines, as long as they originate from embryos that were discarded during the IVF process and donated, with proper informed consent, to research. Government funds still may not be used, however, to create an embryo specifically to destroy it for research purposes, or to create or study stem cells derived from embryos generated by other methods, including cloning and parthenogenesis, in which the egg is directly activated to start dividing and generate an embryo.

In establishing standard criteria for obtaining informed consent from potential donors, the NIH said its main goal was to separate the donation process from the IVF process in order to ensure that donors understand that their IVF experience will not be affected in any way by their decision to discard or donate unused embryos. Donors must be specifically advised that their embryos may be used for stem-cell studies, and may result in commercial products for which they should not expect any financial or medical benefit.

The informed-consent guidelines reflect concerns expressed by researchers, IVF consumers and ethicists that while nobody can predict how donated embryos may end up being used in research, couples undergoing IVF should be made fully aware of the widest range of possibilities. Overall, the NIH rules took into account 49,000 comments submitted to the agency by scientists, patient advocates, medical and religious organizations, private citizens and members of Congress during a public comment period.